Thermal processing torches, such as plasma arc torches, are widely used in the heating, cutting, gouging, and marking of materials. A plasma arc torch generally includes an electrode, a nozzle having a central exit orifice mounted within a torch body, electrical connections, passages for cooling, and passages for arc control fluids (e.g., plasma gas). A swirl ring can be used to control fluid flow patterns in the plasma chamber formed between the electrode and the nozzle. In some torches, a retaining cap can be used to maintain the nozzle and/or swirl ring in the torch body. In operation, a plasma arc torch produces a plasma arc, which is a constricted jet of an ionized gas with high temperature and sufficient momentum to assist with removal of molten metal. Power used to operate plasma arc torches can be controlled by a power supply assembly of a plasma operating system. The power supply and/or metering console, which is often located distant relative to the torch (e.g., several meters), can include a plurality of electronic components configured to control and supply an operational current to the plasma arc torch, the gas flows provided to the plasma arc torch, and, in some cases, motion of the plasma arc torch. This distance between the torch and the power supply/metering console can vary system to system and installation to installation.
In plasma arc cutting systems, transient state electrode life, cut quality and consistency, and overall operations can be affected by or is dependent upon ramp times (e.g., the rate at which plasma current and/or plasma gas rises and drops during start-up and shut down), which can be selected during process parameter development for a given system. These process parameters (i.e., waveforms) typically reside in the power supply (often many meters from the actual torch tip) and are independent of the system configuration being used. Some systems are configured to implement certain gas during transition, start up, or shut down profiles and gas characteristics based on the desired characteristics of the arc during use. For example, some systems can provide desirable gas flow or current profile combinations for shut down.